ABSTRACT: Climate-induced variability of phytoplankton size structure influences primary productivity, marine food web dynamics, biosedimentation and exchange of CO₂ between the atmosphere and ocean. Investigation of phytoplankton size structure in the Arctic Ocean is important due to rapid changes in its ecosystems related to increasing temperature and declining sea ice cover. We estimated the contribution of surface micro-, nano- and picophytoplankton to the total carbon biomass, chlorophyll a concentration and primary production in the Kara and Laptev Seas and investigated the relationships of these phytoplankton size groups with environmental factors which determine their spatial variability. Additionally, we compared chlorophyll specific carbon fixation rate, specific growth rate and carbon to chlorophyll ratios among different phytoplankton size groups. The investigation was carried out from August to September 2018. Generally, picophytoplankton was dominant in terms of chlorophyll a and primary production in the whole study area. The spatial variability of phytoplankton size classes was influenced by river discharge and relied mainly on water temperature, salinity and dissolved silicon concentration. Microphytoplankton prevailed across the river runoff region under conditions of low salinity and relatively high water temperature, while picophytoplankton was predominant under conditions of high salinity and low water temperature. Our study is the first to characterize size-fractionated phytoplankton abundance in the Kara and Laptev Seas, and provides a baseline for future assessment of the response of Kara and Laptev Sea ecosystems to climate-induced processes using phytoplankton size structure.

中文翻译：

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卡拉和拉普捷夫海的大小分等浮游植物：环境控制和空间变异

摘要：气候引起的浮游植物大小结构的变化会影响初级生产力，海洋食物网动态，生物沉降以及大气与海洋之间的CO ₂交换。由于温度升高和海冰覆盖减少导致生态系统的快速变化，因此对北冰洋浮游植物大小结构的研究非常重要。我们估计了表面微浮游植物，纳米浮游生物和微微浮游植物对总碳生物量，叶绿素a的贡献。在卡拉和拉普捷夫海中的浓度和初级生产，并研究了这些浮游植物大小群与确定其空间变异性的环境因素之间的关系。此外，我们比较了不同浮游植物大小组之间的叶绿素比色固碳率，比生长率和叶绿素比。调查于2018年8月至2018年9月进行。一般而言，浮游植物在叶绿素a方面占主导地位。和整个研究区域的初级生产。浮游植物大小类别的空间变异性受河流流量的影响，并且主要取决于水温，盐度和溶解硅的浓度。在低盐度和较高水温的条件下，微生浮游植物在整个河流径流地区盛行，而在高盐度和低水温的条件下，浮游植物占主导地位。我们的研究首次描述了卡拉海和拉普捷夫海的大小分等级浮游植物的丰度，并为未来评估卡拉海和拉普捷夫海生态系统对使用浮游植物大小结构的气候诱发过程的响应提供了基线。